The checkmark next to the "Show Editor Toolbar" menu item can get out of sync with actual setting.
1) Open a file for editing in the NetBeans editor.
2) Click View->"Show Only Editor"
3) Click View->"Show Editor Toolbar"
4) Click View->"Show Only Editor"
5) Click View->"Show Editor Toolbar"
6) There's now a checkmark next to View->"Show Editor Toolbar", even though there is no editor toolbar showing.
It seems the checkbox in the menu is inverted on every click rather than properly being bound to the underlying "toolbarVisible" preference from the java.util.prefs.Preferences system, which is (rightly) modified by the "Show Only Editor" action.
(This bug report is a copy of the old BugZilla bug https://bz.apache.org/netbeans/show_bug.cgi?id=240513 .)